Abstract: The effect of single-layer thickness of layup material on the modal frequency of large wind turbine blades is studied to investigate the coupling mechanism of single-layer thickness of layup material. By using the Box-Behnken method to design experiments,the response surface model between the single-layer thickness of the blade ply material and the first-order modal frequency is established to reveal the influence of the single-layer thickness of different ply materials on the modal frequency of the blade. Further,an optimization mathematical model with the first two orders of the blade modal frequency as the optimal target and the single-layer thickness of the layup material as the design variable is proposed,which uses a combination of genetic algorithm and finite element method for global optimization. The results show that the first-order falpwise and edgewise frequencies of the blade are increased by0.07 Hz after optimization.